Is it permissible for my brother to buy an apartment in France through a bank that would purchase it then sell it to him in installments with interest, knowing that rent is expensive, it is difficult for him to save, and he aims to settle down while living abroad and save money, and does necessity permit that in a non-Islamic country?

If the bank buys the house for itself first, and then sells it to your brother for a profit, this is a permissible Murabahah (cost-plus-profit sale) and not a usurious loan. However, if the bank pays the price on behalf of the buyer and then collects it from him with added interest, this is a usurious loan that is not permissible except in cases of necessity that permit committing what is forbidden. What is mentioned about your brother's situation is not considered a necessity. The limit of necessity is when one fears perishing or unbearable hardship, or the inability to achieve the minimum standard of living for the poor.